1. Field of the Invention
This invention relates particularly, but not exclusively to the production of so-called Kretek cigarettes comprising tobacco and cloves as an additive, which are smoked predominantly in Indonesia. The invention also finds application in the preparation of cigarette fillings comprising tobacco and any other partly fibrous herbal or spice additive.
2. History of the Related Art
The Kretek cigarette is flavored with the spice clove; the filling typically containing 20% clove but can be up to 40% clove. The remainder of the filling is normal tobacco. The cigarette has the distinctive smell of clove oil and when smoked it produces a crackling sound and the smell of burning incense.
The clove is harvested as a flower bud and is then dried in the sun. It comprises an elongated ovule, four prominent sepals and a small bud of petals and stamens with distinct pollen containing anthers. The ovule and sepals are robust, but the bud is fragile.
The distinctive aromatic and taste qualities of cloves arise from soluble and volatile compounds or oils. The major component is the phenol eugenol which makes up about 90% of the aromatics in the clove. The total aromatic content of the clove which varies with agronometric effects is typically 17% but can rise to around 21%. There are differences in the distribution of aromatic oil within the clove plant. While steam distillation of the flower bud yields about 15% of oil, the stems and leaves only yield about 6% and 2-3% respectively.
The cloves are generally twice the cost of the tobacco, but can cost considerably more in a year with a poor harvest.
As shown in the flow diagram of FIG. 1 of the accompanying drawings, the cloves are, at present, prepared for use in Kretek cigarettes by first soaking in water for several hours and then draining overnight before cutting. The cloves are cut by a type of mill, comprising a horizontal axis rotating drum having serrated teeth on its outside surface and a fixed cutting blade set close to the surface. The cloves are fed to the junction of the blade with the drum and dragged past the cutting blade by the serrated teeth. The cutting action is ragged and degrades the cloves. It generates small particles which when dried are dust and thus are lost from the cutting stage. The cutter capacity is low so that many cutters are required.
The cloves are then dried again in the sun and then blended with already cut tobacco for making into cigarettes. The yield is low as more dust is lost from the drying stage so that as much as 15% in total of the original cloves may be lost as dust containing the desired aromatic parts.
The industry would like to mechanise the drying process as sun drying is interrupted by the weather, and thus stocks of dried material have to be built up and held in store in advance. Attempts to do this have resulted in further degradation of the delicate bud and loss of dust with further reduction in yield. Oils and other aromatics are also lost by evaporation due to the high drying temperatures required by a practical sized drier, considered as alternatives to sun drying. A total of up to 40% of the desirable clove oil (Eugenol) can be lost in such processing. Further such losses accumulate at all process stages. During wetting prior to cutting aromatics are lost by solution. During handling, cutting and drying much of the more fragile material which contains the highest aromatic levels is reduced to a non-usable dust. During drying further aromatics are lost by distillation.
In smoking products, flavor generation depends on the composition of the materials combusted and their temperature and oxygenation during combustion. Hence flavor generation is highly influenced by the size and location within the cigarette of the flavor generators. Over large particles tend to generate less flavor than finely cut strands. At the same time it is known in the cigarette industry that the major flavor contribution is generated by that material which lies within about 0.5 mm of the periphery. Clove material currently incorporated into the cigarette tends to be large and robust which tends to limit its flavor contribution due to its size and location relative to the cigarette periphery.
An object of this invention is a more economical method of producing cigarettes with additives in the tobacco particularly Kretek cigarettes in which the additive is processed in such a manner that the usable additive yield is higher and the additive is used more effectively within the cigarettes so that less of the additive is required to flavor the tobacco.